ENHANCEMENT OF IN-VITRO GROWTH OF PAPAYA MULTISHOOTS BY AERATION

Efficient micropropagation of papaya (Carica papaya L.) has become cru cial for multiplication of specific sex types of papaya or transgenic lines resistant to virus infection. In this study, aeration at differe nt intervals with a 0.02 mu m filter disc in the closure of culture fl asks ensured exchange of gas components. The effect of aeration on dev elopment of multibuds to multishoots was investigated. Multibuds grown , in culture flasks after one-week without aeration followed by a two- week aeration treatment caused a 41% increase in the number of shoots greater than or equal to 0.5 cm, 42% increase in leaf expansion, and 1 7% increase in leaf numbers in comparison with unaerated materials. Et hylene and oxygen concentrations in the culture flasks were measured b y gas chromatography and oxygen electrode at weekly intervals during t he culture period. Oxygen concentrations were slightly different betwe en aerated and unaerated culture flasks. Ethylene in the unaerated fla sk reached the highest level (0.11 ppm) 2 weeks after the treatment, w hile accumulation of ethylene in the aerated flasks was not detected. The multishoots grown for 3 weeks without aeration showed growth retar dation on leaves and epinasty on petioles.